Bump version, fix gemspec permission
Add Model#expect, support block at post/pre config

Now we can deal with pager and additional PW prompts, such as 'enable'

Examples in IOS model how to use.

The Telnet implementation is particularly fugly, I just need one line in
'waitfor' to handle pager while waiting for prompt, but couldn't figure
out clean way to do it, so needed to rewrit whole Telnet#waitfor just to
add that line.